The design of this study has several limitations. First, the retrospective assessment of traumatic events during childhood may be influenced by uncontrolled recall bias45. However, previous reviews have suggested that retrospective self-reports concerning childhood abuse are more likely to be biased toward underreporting than exaggeration4647. Second, the retrospective nature of the AAO assessment also provides a source of potential recall bias, although previous data in this area suggests that this is unlikely4849. Third, current mood state may lead bipolar patients to under- or over report histories of childhood trauma. We did not adjust CTQ scores for the presence of residual mood symptoms, which we presumed to be very minor, given that we assessed patients during remission periods. As such, potential mood determined biases in early trauma reporting are minimized. Fourth, we did not extensively investigate the genetic structure of SLC6A4, focusing only on the promoter region, nor epigenetic mechanisms. Finally, after correction for multiple testing, we also did not reach significance for in-depth investigations of trauma subtypes. We also were not able to totally replicate our results. This issue was
